Coherent Reflection from a Rough Interface Over an Inhomogeneous Transition Fluid Layer

Abstract

This paper considers plane-wave reflection from a rough interface over a transition layer within which the density and the sound speed vary simultaneously and continuously. By applying the Kuperman and Schmidt's formulation based upon the first-order boundary perturbation method, the coherent component of the reflection field may be conveniently solved by replacing the boundary conditions for the smooth interface with a set of effective boundary conditions. In contrast to the traditional analysis that the medium is generally discretized into a number of layers, the present study treats the transition layer as a whole by properly choosing the variations of the acoustic properties within the layer. The results for the coherent reflection coefficients in relation to various relevant parameters are generated and analyzed. It was found that the coherent reflection coefficient decreases as frequency increases. Also, it was shown that the root-mean-square roughness is the dominant factor in determining the coherent reflection coefficient, while the spatial correlation of the rough surface can have only a minor effect.